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Copyright 1991 David Jurgens |
INT 14 - BIOS Asynchronous Communications Services
For more information, see the following topics:
INT 14,0 Initialize serial port parameters
INT 14,1 Send character in AL
INT 14,2 Receive character in AL
INT 14,3 Get Serial port status
INT 14,4 Extended initialize (PS/2)
INT 14,5 Extended communication port control (PS/2)
- all functions have:
AH = function number
AL = character to send or receive
DX = zero based RS232 card number
- all registers are preserved except AX
- these functions use hardware flow control
- used by DOS MODE to redirect LPTx output to a serial device
- see individual functions for more data
BIOS Asynchronous Communications Services (Status)
│7│6│5│4│3│2│1│0│ AL modem status
│ │ │ │ │ │ │ └──── clear to send status changed
│ │ │ │ │ │ └───── data set ready status changed
│ │ │ │ │ └────── trailing edge ring indicator
│ │ │ │ └─────── receive line signal changed
│ │ │ └──────── clear to send
│ │ └───────── data set ready
│ └────────── ring indicator
└─────────── receive line signal detected
│7│6│5│4│3│2│1│0│ AH port status
│ │ │ │ │ │ │ └──── data ready
│ │ │ │ │ │ └───── overrun error
│ │ │ │ │ └────── parity error
│ │ │ │ └─────── framing error
│ │ │ └──────── break detect
│ │ └───────── transmit holding register empty
│ └────────── transmit shift register empty
└─────────── time out (N/A for functions 1 and 2)
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| Esc or Alt-X to exit |
int 14 |
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